Why do dogs bark?

This is a write-up of a discussion I took part in on the BBC 4 show “It’s Only A Theory” in November 2009. You’ll be glad to know the panel accepted my theory.

Dogs evolved from wolf-like creatures about 10-12,000 years ago, by exploiting the new ecological niche formed by the permanent habitations of human agriculturalists. When some humans moved from hunter-gathering to a more settled farming community, their waste products became an exploitable food source. In order to take advantage of that niche, proto-wolf/dogs had to stay long enough to consume more calories than extreme fearfulness cost through running away. The proto-dogs with less tendency to run away when humans appeared prospered at the dump, whilst the proto-wolves ran away.

Dogs domesticated themselves by natural selection through breeding together with other dogs that also didn’t run away from the dump.

We know from experiments with silver foxes that breeding together less fearful individuals (those with “reduced flight distance”) results in paedomorphosis: the retention of juvenile characteristics into adulthood. As well as increasing “friendliness”, paedomorphosis has a number of allied effects: floppy ears, curly tails, piebald coats and the tendency to bark.

The physical shape of domestic dogs impoverishes their body language compared to their wilder relatives. It is further diminished by breeding dogs with squashed and wrinkled faces, pendulous ears, drooping dewlaps, tightly curled tails, hair over their eyes, solid coloured coats, undershot and overshot jaws. We breed them like this. We breed dogs that find it very difficult to communicate in the way their fellow canids would understand it. This comparative lack of expression makes it even more difficult for them to communicate with another species; especially one that isn’t watching them most of the time.

Most scientific experiments place domestic dog barks into about six groups of communication: fear, anger, frustration, loneliness, pleasure and excitement. If a dog spontaneously barks, it will be for one of those reasons.

A recent study developed a computer programme that could distinguish these groups of barks from each other, but only with a 43% success rate, which sounds quite poor, until they tested the same barks on human listeners, who could only tell them apart 40% of the time. This is a spectacularly poor method of communicating, if it is effective only 4 times in 10.
But what does barking do for dogs? It makes us look at them. It adds emphasis to their more usual canine communication.
We have undoubtedly selectively bred guard dogs to enhance their tendency to bark, but perhaps we’ve unconsciously bred all dogs to use barking as a method of drawing attention to their body language.

If our dog stares at the front door, body stiff, eyes wide and lips curled, would we know that a car had pulled up outside if they didn’t bark as well?

If dogs didn’t live with us they wouldn’t have developed the paedomorphic tendency to bark.

If we hadn’t impoverished their body language they wouldn’t need to bark to tell other dogs that they are excited or angry.

If we paid their real communication more attention, they wouldn’t need to shout to make themselves understood.